Download Basaloid Squamous Carcinoma arising at Splenic Flexure of Colon

Jpmer
jpmer
10.5005/jp-journals-10028-1231
Basaloid Squamous Carcinoma
arising at Splenic Flexure of Colon
Case Report
Basaloid Squamous Carcinoma arising
at Splenic Flexure of Colon
1
Gnanapriya Vellaisamy, 2Gayatri Ravikumar, 3Julian Crasta, 4Pritilata Rout
ABSTRACT
Basaloid squamous carcinoma occurs most commonly in the
upper aerodigestive tract. In the colon, the most common location is in the anal canal and is rarely reported proximal to the
anal verge. Six cases are reported in the published literature,
of which five are located distal to the splenic flexure. Outside
the anal canal, it has been postulated that they arise from the
basal cells, squamous metaplastic cells, or the cloacogenic
embryologic cell rests. We report a case of a 57-year-old male
patient who presented with short duration of abdominal pain and
weight loss. Computed tomography (CT) abdomen revealed an
irregular circumferential thickening in the terminal transverse
colon, splenic flexure, and proximal descending colon. Colonoscopy showed a stricture in the splenic flexure, which was
suspected for malignancy. Endoscopic biopsy was reported as
poorly differentiated carcinoma. Left extended hemicolectomy
was done, and a diagnosis of basaloid squamous carcinoma
was made on histopathology. The tumor cells were positive for
P63, CK 5/6; focally for CDX2; and negative for CK20, chromogranin, and CD56, confirming the histopathological diagnosis
of basaloid squamous carcinoma. The patient is currently on
adjuvant chemotherapy.
Keywords: Basaloid carcinoma, Colon, Splenic flexure.
How to cite this article: Vellaisamy G, Ravikumar G, Crasta J,
Rout P. Basaloid Squamous Carcinoma arising at Splenic
Flexure of Colon. J Postgrad Med Edu Res 2017;51(1):33-36.
Source of support: Nil
Conflict of interest: None
INTRODUCTION
Conventional squamous cell carcinoma (SCC) is rare
in the colon and accounts for nearly 0.1 to 0.25 cases
per 1,000 colorectal carcinomas.1,2 Basaloid squamous
cell carcinoma (BSCC), otherwise called as transitional
cloacogenic carcinoma, occurs most commonly in the
upper aerodigestive tract, cervix, and thymus. In the
colon, the most common location is the anal canal and is
rare outside it. In the anal canal, it usually arises from the
anal transitional epithelium or the cloacogenic remnants.
1
Lecturer, 2Assistant Professor, 3Professor, 4Professor and Head
1-4
Department of Pathology, St. John’s Medical College and
Hospital, Bengaluru, Karnataka, India
Corresponding Author: Gnanapriya Vellaisamy, Lecturer
Department of Pathology, St. John’s Medical College and
Hospital, Bengaluru, Karnataka, India, e-mail: drvgnanapriya@
gmail.com
Some ultrastructural studies revealed that they may also
arise from the transtitional lining of the anal ducts or from
the totipotential basal cells of the squamous epithelium.3-5
Outside the anal canal, it has been postulated that the
tumor may arise from cloacogenic embryologic rests,
squamous metaplastic cells, or the totipotential basal
cells.6-8 Till date, only six cases of BSCs of the colon have
been reported in the published literature, with only one
occurring at the splenic flexure and the rest distal to it.6-11
Here, we report one such rare case of BSC occurring at
the colonic splenic flexure.
CASE REPORT
A 57-year-old male patient presented with complaints
of severe continuous abdominal pain in the left lower
quadrant for 3 months and weight loss of about 6 kg in
2 months. Other than a history of tubercular epididymitis,
there was no other significant medical history. On per
abdominal examination, a soft mass was felt in the left
lumbar region. The laboratory investigations (including
complete blood count, blood urea nitrogen, creatinine,
blood sugar, serum electrolytes, and liver function tests)
revealed only mild anemia. The carcinoembryonic antigen
was mildly elevated at 8.91 µg/L (normal is 0–2.5 µg/L).
Contrast-enhanced computed tomography (CT) abdomen
showed an irregular circumferential thickening involving
terminal transverse colon, splenic flexure, and proximal
distal colon, with features suggestive of carcinoma colon.
There were no signs of metastasis. On colonoscopy, an
ulcerated stricture was identified at a distance of 40 cm
from the anal verge, which was suspected for malignancy.
Scope could not be negotiated, and rest of the mucosa
was normal (Fig. 1).
On colonoscopic biopsy, a diagnosis of poorly differentiated carcinoma was made. Left extended hemicolectomy
was done. Intraoperatively, a large ulceroproliferative
splenic flexure mass measuring 15 × 15 cm was identified
with multiple mesocolon lymph nodes. Liver surface was
normal. The postoperative period was uneventful. On
gross examination, a circumferential ulceroproliferative
lesion measuring 16 × 8 × 8 cm was seen infiltrating
the entire thickness of colon (Fig. 2). On microscopic
examination, the neoplasm was composed of moderately
pleomorphic atypical cells arranged in lobules and
nests with peripheral palisading of basaloid cells and
Journal of Postgraduate Medicine, Education and Research, January-March 2017;51(1):33-36
33
Gnanapriya Vellaisamy et al
Fig. 1: Colonoscopy image showing an ulcerated stricture
Fig. 2: Ulceroproliferative growth infiltrating into the
perimuscular connective tissue
Fig. 3: The neoplasm comprises lobules and nests of atypical cells
with central necrosis (arrow mark) (hematoxylin–eosin stain. Original
magnification 10×)
Fig. 4: High-power view showing peripheral palisading of basaloid
cells with central squamous differentiation (hematoxylin–eosin stain.
Original magnification 40×)
central areas of necrosis in few of the lobules. The
individual basaloid cells exhibited oval hyperchromatic
nuclei, inconspicuous nucleoli, and scant eosinophilic
cytoplasm. The center of the lobules showed squamous
differentiation with keratin pearl formation (Figs 3 and 4).
Mitotic figures were frequent. The adjacent stroma showed
moderate desmoplasia and moderate lymphocytic host
response. The neoplasm was seen infiltrating beyond
the muscularis into the perimuscular connective tissue.
Perineural invasion and lymphovascular emboli were
absent. The overlying epithelium did not show any
evidence of squamous metaplasia or dysplasia. Out of the
11 pericolic lymph nodes available for assessment, one
node showed metastasis without perinodal extension.
Immunohistochemistry was performed using polymer
technique for the following antibodies: CK20 (mouse
monoclonal IT ks 20.8, BioGenex), CK5/6 (rabbit
monoclonal Ep67, PathnSitu), p63 (mouse monoclonal
4A4, BioGenex), CD56 (mouse monoclonal 123C3,
DAKO), Chromogranin (mouse monoclonal LK2H10/PR,
DAKO), and CDX2 (mouse monoclonal CDX2, DAKO).
The neoplastic cells were diffusely positive for CK5/6, P63;
focally for CDX2; and negative for CK20, chromogranin,
and CD56 (Figs 5 and 6). The histopathology was
supported by the immunoprofile, and a diagnosis of BSC
was made. The patient was started on 1st cycle of adjuvant
chemotherapy, which included bevacizumab 2.5 mg/kg
body weight, oxaliplatin 85 mg/m2 over 2 hours, and
capecitabine 1,000/m2/d for the first 2 weeks of each
3-week cycle. The patient is on regular treatment and
follow-up. No complications have been reported till date.
34
DISCUSSION
Conventional SCCs are rarely reportedly in the colon.
Before making a diagnosis of primary SCC in the colon,
the following criteria need to be considered: (1) Care
Jpmer
Basaloid Squamous Carcinoma arising at Splenic Flexure of Colon
Fig. 5: CK5/6 showing membranous positivity in the neoplastic
cells (hematoxylin–eosin stain. Original magnification 40×)
Fig. 6: P63 showing diffuse nuclear positivity in the neoplastic
cells (hematoxylin–eosin stain. Original magnification 40×)
should be taken to exclude contiguous spread from other
sites; (2) direct extension of primary tumor from anal
canal (in case of rectal SCCs); (3) affected bowel should
not be involved in fistulas lined by squamous cells; and
(4) histological confirmation of SCC is mandatory.1 Our
case had fulfilled all the above-mentioned criteria.
The BSC, also known as transitional cloacogenic
carcinoma, occurs in both sexes, but is more common in
males between 60 and 80 years of age. It usually arises
from the anal transitional epithelium, otherwise called as
cloacogenic membrane, bounded superiorly by the rectal
mucosa and inferiorly by the pectinate line. It may also
arise from the anal ducts with transitional lining epithelium or from the basal cells.3-5 Cloacogenic carcinomas
have a range of microscopic patterns of which two are
well recognized: Well-differentiated transitional form as
it resembles urothelial carcinoma, and the basaloid form,
as it simulates cutaneous basal cell carcinoma (BCC).12
The BSC is rare in other sites of the colon. Strate et al6
had reported the first case of BSC in the sigmoid colon
above the pelvic brim at the peritoneal reflection. In the
literature, six cases are reported, of which five are located
distal to the splenic flexure.6-11 In this case, the tumor is
located in the distal part of the transverse colon, splenic
flexure, and proximal part of descending colon. Intriguing
is the origin of the BSCs in the colon. Three mechanisms
are postulated: (1) Preexisting squamous metaplasia of the
colonic glands that later became dysplastic from which
the tumor evolves; (2) it may also arise from cloacogenic
embryological transitional cell rests; or (3) from the totipotential basal cells.6-8 We did not find squamous metaplasia
or cloacogenic remnants in our case.
When the tumor arises close to the anal canal, it is
difficult to distinguish BSCs from BCCs. The retraction
spaces around the infiltrating nests, lack of increased
atypical mitosis, and absence of precursor lesions aid in
differentiating BCCs from BSCs. In the present case, the
location of the tumor was far from the anal verge, and the
histological differentials considered were adenosquamous
carcinoma or a neuroendocrine carcinoma due to presence
of rosette-like structures around the necrotic foci in some
sections. The characteristic histological features of BSC that
differentiate it from small cell carcinoma are presence of
central comedo-like necrosis, central squamous differentiation, and peripheral palisading of basaloid cells. Immunohistochemically, these cells are immunoreactive for CK5/6,
P63, and 34βE12, whereas the small cell carcinomas are
positive for CD56, chromogranin, and synaptophysin.
Histological diagnosis of BSCs on diagnostic colonoscopic biopsies is often difficult due to smaller tissue
sampled and presence of necrosis. These tumors may
also produce ectopic hormones, such as parathyroid hormone, adrenocorticotropic hormone (ACTH), or ACTHlike substance.6,9 Although the clinical presentation, CT
findings, and gross appearance of these neoplasm and
further adjuvant chemotherapy are similar to conventional adenocarcinomas, the prognosis has been reported
to be worse as compared with the latter.13 These tumors
pose a diagnostic challenge due to their rare location in
the splenic flexure, the difficulty in diagnosis on initial
confirmatory colonoscopic biopsies, and histological
similarities with small cell neuroendocrine and BCCs in
less-differentiated variants.
REFERENCES
1. Williams GT, Blackshaw AJ, Morson BC. Squamous carcinoma of the colorectum and its genesis. J Pathol 1979
Nov;129(3):139-147.
2. Gelas T, Peyrat P, Francois Y, Gerard JP, Baulieux J, Gilly FN,
Vignal J, Glehen O. Primary squamous-cell carcinoma of the
rectum: report of six cases and review of the literature. Dis
Colon Rectum 2002 Nov;45(11):1535-1540.
3. Klotz RG Jr, Pamukcoglu T, Souilliard DH. Transitional
cloacogenic carcinoma of the anal canal. Clinicopathologic
Journal of Postgraduate Medicine, Education and Research, January-March 2017;51(1):33-36
35
Gnanapriya Vellaisamy et al
4.
5.
6.
7.
8.
36
study of three hundred seventy-three cases. Cancer 1967
Oct;20(10):1727-1745.
Fisher ER. The basal cell nature of the so-called transitional
cloacogenic carcinoma of anus as revealed by electron microscopy. Cancer 1969 Aug;24(2):312-322.
Grinvalsky HT, Helwig EB. Carcinoma of the anorectal
junction. I. Histological considerations. Cancer 1956 MayJun;9(3):480-488.
Strate RW, Richardson JD, Bannayan GA. Basosquamous
(transitional cloacogenic) carcinoma of the sigmoid colon.
Cancer 1977 Sep;40(3):1234-1239.
Hall-Craggs M, Toker C. Basaloid tumor of the sigmoid colon.
Hum Pathol 1982 May;13(5):497-500.
Ranaldi R, Sisti S, Librari ML, Suraci V, Bearzi I. Basaloid
carcinoma of the sigmoid colon: report of a case. Pathologica
1988 Sep-Oct;80(1069):595-600.
9. Newell KJ, Penswick JL, Driman DK. Basaloid carcinoma of
the colon arising at the splenic flexure. Histopathology 2001
Mar;38(3):232-236.
10. Ha TH, Jeon TJ, Park JY, Jang YH, Kim DH, Ryu MJ,
Sinn DH, Oh TH. A case of basaloid squamous cell carcinoma
of rectosigmoid colon. Korean J Gastroenterol 2013 Dec;62(6):
375-378.
11. Jaswal TS, Gupta S, Singh S, Marwah N, Marwah S, Arora B.
Basaloid carcinoma of descending colon. Indian J Gastroenterol 2002 Jul-Aug;21(4):159-160.
12. Gillespie JJ, Mackay B. Histogenesis of cloacogenic carcinoma.
Fine structure of anal transitional epithelium and cloacogenic
carcinoma. Hum Pathol 1978 Sep;9(5):579-587.
13. Comer TP, Beahrs OH, Dockerty MB. Primary squamous cell
carcinoma and adenocanthoma of the colon. Cancer 1971
Nov;28(5):1111-1117.